As is well known, shifting between gear ratios in manual transmissions is caused by selectively coupling one of the gearsets for driving an output shaft at a predetermined speed ratio relative to the input shaft. Most manual transmissions include a plurality of synchromesh gearsets with an input gear driven by one of the shafts and a speed gear rotatably supported on the other shaft. A shift system associated with the transmission includes a shift sleeve that is moveable for releaseably coupling the speed gear to its respective shaft, and a synchronizer unit operable for establishing speed synchronization between the speed gear and shaft prior to engagement of the shift sleeve. The shift system further includes one or more rails which support range forks that each have a U-shaped fork segment adapted for retention in a circumferential groove formed in the shift sleeve. In manual shift transmissions, a gearshaft lever is connected via mechanical linkages to control coordinated movement of the range forks for moving the shift sleeves so as to establish the selected gear ratio. In automated versions of manual transmissions, an electrically-controlled or hydraulically-controlled actuator is used to control movement of the range forks.
In most conventional transmissions, the range forks are forged products which require a significant amount of rough and finish machining. A critical design factor that has limited range forks to forged products is the strength requirement of the fork segment which must be able to withstand large and repeated loading during gear shifts. Other attempts to mold/cast range forks with load-absorbing fork inserts have met with limited success. Therefore, a need exists to develop alternative range fork concepts which overcome the shortcomings of the prior art.